A new approach is proposed to analyze the settlement behavior for single pile embedded in layered soils. Firstly, soil layers surrounding pile shaft are simulated by using distributed Voigt model, and finite soil laye...A new approach is proposed to analyze the settlement behavior for single pile embedded in layered soils. Firstly, soil layers surrounding pile shaft are simulated by using distributed Voigt model, and finite soil layers under the pile end are assumed to be virtual soil-pile whose cross-section area is the same as that of the pile shaft. Then, by means of Laplace transform and impedance function transfer method to solve the static equilibrium equation of pile, the analytical solution of the displacement impedance fimction at the pile head is derived. Furthermore, the analytical solution of the settlement at the head of single pile is theoretically derived by virtue of convolution theorem. Based on these solutions, the influences of parameters of soil-pile system on the settlement behavior for single pile are analyzed. Also, comparison of the load-settlement response for two well-instrumented field tests in multilayered soils is given to demonstrate the effectiveness and accuracy of the proposed approach. It can be noted that the presented solution can be used to calculate the settlement of single pile for the preliminary design of pile foundation.展开更多
Objective. To evaluate the diagnostic criteria for the localization of acquired arteriovenous fistulas (AVFs) by color Doppler flow imaging (CDFI) based on the features of their hemodynamic changes. Methods. The shape...Objective. To evaluate the diagnostic criteria for the localization of acquired arteriovenous fistulas (AVFs) by color Doppler flow imaging (CDFI) based on the features of their hemodynamic changes. Methods. The shape and hemodynamic changes of involved vessels which could be helpful to localize the sites of fistulas were studied according to the observation of 10 cases of acquired AVFs. Results. The sites of the fistulas could be shown by two dimensional ultrasonography and color flow imaging in 40%and 80%cases, respectively. In all cases, turbulent high velocity flow was present at the sites of the fistulas, low resistant flow was present in the arteries proximal to the fistulas, and artery like flow was detected in the veins. Conclusion. CDFI was accurate for the localization of acquired AVFs, which were mainly localized by their hemodynamic changes shown by pulse Doppler ultrasound.展开更多
AIM:To review percutaneous transhepatic portal venoplasty and stenting(PTPVS)for portal vein anastomotic stenosis(PVAS)after liver transplantation (LT). METHODS:From April 2004 to June 2008,16 of 18 consecutive patien...AIM:To review percutaneous transhepatic portal venoplasty and stenting(PTPVS)for portal vein anastomotic stenosis(PVAS)after liver transplantation (LT). METHODS:From April 2004 to June 2008,16 of 18 consecutive patients(11 male and 5 female;aged 17-66 years,mean age 40.4 years)underwent PTPVS for PVAS.PVAS occurred 2-10 mo after LT(mean 5.0 mo). Three asymptomatic patients were detected on routine screening color Doppler ultrasonography(CDUS). Fifteen patients who also had typical clinical signs of portal hypertension(PHT)were identified by contrastenhanced computerized tomography(CT)or magnetic resonance imaging.All procedures were performed under local anesthesia.If there was a PVAS<75%, the portal pressure was measured.Portal venoplasty was performed with an undersized balloon and slowly inflated.All stents were deployed immediately following the predilation.Follow-ups,including clinical course, stenosis recurrence and stent patency which were evaluated by CDUS and CT,were performed. RESULTS:Technical success was achieved in all patients.No procedure-related complications occurred. Liver function was normalized gradually and the symptoms of PHT also improved following PTPVS.In 2 of 3 asymptomatic patients,portal venoplasty and stenting were not performed because of pressure gradients<5 mmHg.They were observed with periodic CDUS or CT.PTPVS was performed in 16 patients.In 2 patients,the mean pressure gradients decreased from 15.5 mmHg to 3.0 mmHg.In the remaining 14 patients,a pressure gradient was not obtained because of>75%stenosis and typical clinical signs of PHT.In a 51-year-old woman,who suffered from massive ascites and severe bilateral lower limb edema after secondary LT,PVAS complicated hepatic vein stenosis and inferior vena cava(IVC)stenosis. Before PTPVS,a self-expandable and a balloonexpandable metallic stent were deployed in the IVC and right hepatic vein respectively.The ascites and edema resolved gradually after treatment.The portosystemic collateral vessels resulting from PHT were visualized in 14 patients.Gastroesophageal varices became invisible on poststenting portography in 9 patients.In a 28-yearold man with hepatic encephalopathy,a pre-existing meso-caval shunt was detected due to visualization of IVC on portography.After stenting,contrast agents flowed mainly into IVC via the shunt and little flowed into the portal vein.A covered stent was deployed into the superior mesenteric vein to occlude the shunt. Portal hepatopetal flow was restored and the IVC became invisible.The patient recovered from hepatic encephalopathy.A balloon-expandable Palmaz stent was deployed into hepatic artery for anastomotic stenosis before PTPVS.Percutaneous transhepatic internal-external biliary drainage was performed in 2 patients with obstructive jaundice.Portal venous patency was maintained for 3.3-56.6 mo(mean 33.0 mo) and all patients remained asymptomatic.CONCLUSION:With technical refinements,early detection and prompt treatment of complications,and advances in immunotherapy,excellent results can be achieved in LT.展开更多
基金Project(50879077) supported by the National Natural Science Foundation of China
文摘A new approach is proposed to analyze the settlement behavior for single pile embedded in layered soils. Firstly, soil layers surrounding pile shaft are simulated by using distributed Voigt model, and finite soil layers under the pile end are assumed to be virtual soil-pile whose cross-section area is the same as that of the pile shaft. Then, by means of Laplace transform and impedance function transfer method to solve the static equilibrium equation of pile, the analytical solution of the displacement impedance fimction at the pile head is derived. Furthermore, the analytical solution of the settlement at the head of single pile is theoretically derived by virtue of convolution theorem. Based on these solutions, the influences of parameters of soil-pile system on the settlement behavior for single pile are analyzed. Also, comparison of the load-settlement response for two well-instrumented field tests in multilayered soils is given to demonstrate the effectiveness and accuracy of the proposed approach. It can be noted that the presented solution can be used to calculate the settlement of single pile for the preliminary design of pile foundation.
文摘Objective. To evaluate the diagnostic criteria for the localization of acquired arteriovenous fistulas (AVFs) by color Doppler flow imaging (CDFI) based on the features of their hemodynamic changes. Methods. The shape and hemodynamic changes of involved vessels which could be helpful to localize the sites of fistulas were studied according to the observation of 10 cases of acquired AVFs. Results. The sites of the fistulas could be shown by two dimensional ultrasonography and color flow imaging in 40%and 80%cases, respectively. In all cases, turbulent high velocity flow was present at the sites of the fistulas, low resistant flow was present in the arteries proximal to the fistulas, and artery like flow was detected in the veins. Conclusion. CDFI was accurate for the localization of acquired AVFs, which were mainly localized by their hemodynamic changes shown by pulse Doppler ultrasound.
文摘AIM:To review percutaneous transhepatic portal venoplasty and stenting(PTPVS)for portal vein anastomotic stenosis(PVAS)after liver transplantation (LT). METHODS:From April 2004 to June 2008,16 of 18 consecutive patients(11 male and 5 female;aged 17-66 years,mean age 40.4 years)underwent PTPVS for PVAS.PVAS occurred 2-10 mo after LT(mean 5.0 mo). Three asymptomatic patients were detected on routine screening color Doppler ultrasonography(CDUS). Fifteen patients who also had typical clinical signs of portal hypertension(PHT)were identified by contrastenhanced computerized tomography(CT)or magnetic resonance imaging.All procedures were performed under local anesthesia.If there was a PVAS<75%, the portal pressure was measured.Portal venoplasty was performed with an undersized balloon and slowly inflated.All stents were deployed immediately following the predilation.Follow-ups,including clinical course, stenosis recurrence and stent patency which were evaluated by CDUS and CT,were performed. RESULTS:Technical success was achieved in all patients.No procedure-related complications occurred. Liver function was normalized gradually and the symptoms of PHT also improved following PTPVS.In 2 of 3 asymptomatic patients,portal venoplasty and stenting were not performed because of pressure gradients<5 mmHg.They were observed with periodic CDUS or CT.PTPVS was performed in 16 patients.In 2 patients,the mean pressure gradients decreased from 15.5 mmHg to 3.0 mmHg.In the remaining 14 patients,a pressure gradient was not obtained because of>75%stenosis and typical clinical signs of PHT.In a 51-year-old woman,who suffered from massive ascites and severe bilateral lower limb edema after secondary LT,PVAS complicated hepatic vein stenosis and inferior vena cava(IVC)stenosis. Before PTPVS,a self-expandable and a balloonexpandable metallic stent were deployed in the IVC and right hepatic vein respectively.The ascites and edema resolved gradually after treatment.The portosystemic collateral vessels resulting from PHT were visualized in 14 patients.Gastroesophageal varices became invisible on poststenting portography in 9 patients.In a 28-yearold man with hepatic encephalopathy,a pre-existing meso-caval shunt was detected due to visualization of IVC on portography.After stenting,contrast agents flowed mainly into IVC via the shunt and little flowed into the portal vein.A covered stent was deployed into the superior mesenteric vein to occlude the shunt. Portal hepatopetal flow was restored and the IVC became invisible.The patient recovered from hepatic encephalopathy.A balloon-expandable Palmaz stent was deployed into hepatic artery for anastomotic stenosis before PTPVS.Percutaneous transhepatic internal-external biliary drainage was performed in 2 patients with obstructive jaundice.Portal venous patency was maintained for 3.3-56.6 mo(mean 33.0 mo) and all patients remained asymptomatic.CONCLUSION:With technical refinements,early detection and prompt treatment of complications,and advances in immunotherapy,excellent results can be achieved in LT.
